Process for making coffee extracts



Spt- 24, 1946. Jv. l.. KELLQGG A 2,408,260

' PROCESS FOR MAKING COFFEE' ExTRAcTs 55 Puiwnf y I @deff-*Mgmt I /W sept. 24, 1946.

| KELLOGGv PROCESS FOR MAKING COFFEE EXTRACTS Filed Sept. 21,. 1942 2 Sheets-Sheet 2 Patented Sept. 24, 1946 PROCESS FOR MAKING COFFEE rEXTRACTS John L. Kellogg, Chicago, 111., assignor to John L. Kellogg & Co., Chicago, Ill.,ja, ,corporation of Illinois Application September 21, 1942,-Sria-1Nlo. 459,104

Thisinvention relates tothe production of coffee extracts, in the form either of dry soluble powder or syrup; and a primary object of the invention is to provide certain novel procedures to be hereinafter described, whereby beverages made from the extracts will have, in avery high degree, the flavor and aroma of beverages made girectly from the roasted and ground coffee A further object is to provide a processfor making coffee extracts which will be eflicient and economical; that is, which will remove from the coffee material, at a relatively low operating cost, a maximum amount of the desired extractable substances. Y f

Coffee substances which give flavor and aroma to the beverages ,made from coffee extracts are in some eases easily volatilized and lostor ltheir flavor and aroma giving vqualities impaired if the material is subjected tof high temperatures. For example, these substances may be lost orim.- paired by the prolonged heat treatments which the material may receive in extracting operations and in the subsequent concentration ofthe extract. 'I'he concentrating operations are usually carried out, in part or Wholly, in a vacuum pan which is an economical procedure but one involving subjecting the extract at a relatively high temperature for a considerable period of time.

In order to avoid the loss or impairment in qua-lity of the avor and aroma vgiving substances of the roasted coffee beanathe present invention contemplates the extraction of .at least a portion .of the extractives, and thesubsequent concentration of the extract, at relatively. low temperatures. 'For example, the concentration maybe effected by freezing the extract. Preferably, however, only a part of the extractives are obtained and the extractconcentrated in this manner. In the preferred form of the process, ac-

cording to the present inventiom an extract is v.

made vand concentrated at low temperature, th'e residue of the coffee kmaterial is subjected to-ex'- tracting and concentrating operations ,at higher temperatures, and the two extracts are then dered extract is the fultimate product, a small quantity of a hydrogenated or partially hydrogenated vegetable oil, preferably coffee oil, the functions of which, at this'stage of the process,

: are rst to effect retention of vcoffee substances that would otherwise be y.volatilized and second to prevent dust formation in the subsequent. drying and pulverizing operations.

In `application `for United States patent led by the applicant January 3, 19.42, Serial No. 425,551, is described and claimed thelexpedient of radding to the coffee material in process, preferably to the. powdered extract or the final syrup, in case the extract is not evaporated to dryness, a certain quantity .of natural coffee oil mixed, preferably, with enough hydrcgenatedl vegetable oil (which may be hydrogenated coffee oil) `to prevent the natural`A coffee oilfrom becoming rancid. The present invention provides anim- .proved process, forlincorporatingthe oilin` the powder or syrup extract.

The process of the present. invention also in.`

.volves preferably the incorporation into the nal extracted powder or syrup, of some at least ofthe low temperature extract, above referred to, together with the natural coffee oil, b-y `a method which facilitates-the introduction of these substances into the final product, with the result that the nal product contains a relativelylarge' quantity of avor and aroma giving substances which have not been subjected to temperatures high enough to involve; their loss by volatilization or impairment inrespect to quality. In applicants United States Patent No. 2,282,138, patented May 5, 1942, for Process for the production of 4soluble coffee extract, is disclosed an extracting .process in which the. coffee material is given successive extracting operations, with heat and agitation and in which the extra-cts move counter-current to the vcoffee material. Inv this patent there is also disclosed a cooking step in which the material before it enters` the. last extracting operation is cooked under steam pressure so as to make possible the removal of additional extraotivesin the extracting'` operation which folloWs-extractives which expedienty the yield of extract is increasedL would not be removable by the usual extraction operation except for this cooking step. By this It has been since discovered, however, that the cooking step, which does not involve agitation orbut little agitation, is more advantageously used at the stage of lthe process from which is derived the final extract going to` the vacuum pan, which '55 vWill. be referred to herein as'the No. 1 extract,

meaning the extract from the rst treatment of the material in the countercurrent extracting system. By cooking the coffee material, which' will preferably, as a matter of economy, be the material from which the preliminary or low temperature extract has been made as a last step in the extractingoperation, a clearer extract is obtained than with the process' of Patent No. 2,282,138, where three extracts, with agitation, are made after the material has been cooked. Th'e cooking coagulates colloids which may then be removed by filtration or centrifuging and this brings about clarification of the extract.

The invention is exemplified in the following specific examples, which, however, should be regarded as typical and informative only and not as limiting the invention to the particulars given therein; the intention being to cover all equiva lents of the process steps described and also all modifications of such processes within the scope of the hereto appended claims.

The drawings appended hereto are flow sheets illustrating the invention. Fig. 1 is a iiow sheet illustrating the process described under the caption Example 1; and Fig. 2 illustrates a modification of this process described under the caption Example 3.

Example 1.-Referring to ow sheet Fig. 1: 35 pounds of roasted and ground coffee is introduced into a vessel I0 with 10 gallons of fresh, cold water, that is, Water at a temperature not in excess of room temperature (70 F.). The material is allowedto soak in vessel I0 for about 1 hour. It is then subjected to a separating operation, preferably by means of a centrifuge I I. The extract from centrifuge II is then frozen at I2, the ice crushed at I3, the crushed ice centrifuged at I4, the liquid frozen again at I5, the ice crushed at I6, and the crushed ice centrifuged at I1. The freezing, crushing and centrifuging operations may be repeated as often as desired in order to obtain as concentrated an extract as may be found necessary. The operations described will give an extract having a density of about 15 to Baume; although to obtain this den-sity a third freezing operation may in some cases be necessary. The ice from centrifuges I4 and I1 is returned by line I8 to the fresh water supply I9 for the soaking vessel III-the Ispecified 10 gallons of fresh water including the water from the returned ice. The low temperature extract from the centrifuge I1 is preferably claried in a clarifying centrifuge, or otherwise by filtration, and is mixed with the No. 1 extract produced by` the counter-current extraction apparatus illustrated at the right-hand side of the flow sheet. This No. 1 extract may be referred to as the high temperature extract. The coffee material from centrifuge II goes through line 2I (fresh coffee may be added if desired-or fresh coffee used exclusively at this place) to the steam cooker 22 which is provided with a steam coil 23 or other suitable heating means. The coffee material entering the cooking vessel 22 through line ZI is mixed with No. 2 extract, entering the vessel through line 24, and the mixture is brought to a boil and boiled for about 5 minutes. The material is then centrifuged at 25, and the solid coffee material is introduced into the extracting vessel 26 which is provided with an agitator 21 and a steam coil 28. Here it is mixed with No. 3 extractI through line 29 and maintained at a temperature of about 125 F. (120-130) for one hour, with agitation. The material i's then centrifuged at 30, the liquid, ex-

tract No. 2, going through line 24 to the QQQKSI 2,2,

as described, and the solids to the extracting vessel 3|, which is provided with agitator 21 and steam coil 28 and into which is introduced about 10 to 13 gallons of fresh water and about half ounce of taka-diastase in the powdered form. The extraction proceeds at a temperature of about F. for one hour, with agitation; after which the material is centrifugedV at 32, the liquid, extract No. 3, going through line 29 to the extracting vessel 26. The extraction at abo-ut 125 F. (120- F.) is for the purpose of giving an optimum temperature for the action of taka-diastase. If other enzymes be used, the extraction temperature will preferably be the optimum temperature forv such enzymes. The process may employ a larger number of extracting operations.

The No. 1 extract from centrifuge 25 is preferably clarified in the clarifying centrifuge 34, and is then introduced into'the vacuum pan 35, operating, for example, at a vacuum of 28 inches of mercury, in which the extract is evaporated to a density of about 3032 Baume. Preferably, and particularly if the extract is to be evaporated to dryness, there is added to the evaporated extract at 36 (or to the extract going to the vacuum pan 35) about one-half ounce of hydrogenated oil, which may be coffee oil or any hydrogenated vegetable oil, and which, in the amount used, does not affect the taste of the extract. The addition of the hydrogenated oil to the material in process is not covered generically herein, as it is disclosed and claimed in applicants co-pending application Serial No. 375,542, filed January 21, 1941.

The low temperature extract from the freezing operation is mixed at 31 with the high temperature extract from the counter-current extracting system. This mixture may -be packaged and sold as a liquid or semi-liquid extract, or may be further concentrated to a thick syrupy consistency; or it may be subjected to a drying operation, pref-- erably of the instantaneous type. The drawings indicate, for this purpose, a pair of drying rolls 38, 38 into the bight of which is introduced the,

liquid from the mixture 31. The rolls will, of course, be provided with the usual doctor blades for scraping off the material, which material may then be reduced to a powder in the pulverizer 39. A single drying roll may be used, in which case the density of the extract mixture need not be quite a-s high as indicated. It will be possible, particularly under these conditions, to omit some or possibly all of the freezing operations. It will also be possible to use spray drying instead of drying upon a'roll or rolls. The introduction of the oil at 36brings about, when the material is subsequently dried, a coating or partial coating of the dry particles with the oil which helps to retain in the dried extract 'some flavor and aroma giving substances which might otherwise Ibe volatilized and lost by the drying operation. The oil also, small in quantity as it is, tends to prevent dust formation in the pulverizing operation. Drying between rolls, or spray drying, is advantageous because, although temperatures may be high, the duration of heat application is very short. By employing the process as described, the final extract will contain extractives, of a more or less volatile character, derived from the low temperature extract, to compensate for the removal, destruction or deterioration of the corresponding constituents of the coffee material which occur, to some extent, as a consequenceof the relatively high temperatures prevailing in the counter-current extracting system and also in the vacuum pan employed for evaporating or concentrating the extract from the lcounter-cur-rent extracting system. 'In this way, Awithout sacriiiceof yields, beverages made from the extract-have the iiavor and aroma of beverages made from roasted and groundcoffeebeans. n

Example 2.-Instead of using fresh water in the preliminary low temperature extraction and concentrating, the extract ,byY freezing, it will be possible to omitl the `freezing operations and obtain an extract of sufficiently high density byusing instead of vfresh Water for the preliminary soaking operation an extract from the .counter-current extracting system. Y Or this expedient may be combined with theireez'ing process. In anycase, a `vllovv temperature extract containing -extractives, which are preserved because of the low temperature'maintai-ned in ,this part of the process, is mixed lwith the more concentrated extract obtained through the use of the relatively high temperatures lso as to give the lfinal extract mixture qualities and characteristics which the extractfrom the usual coffee extracting system does not have, -or in which it is more -or less deficient, because of the high temperatures to which the entire material is subjected in the extracting, concentrating and drying operations. 'The employment of diastase in connection 'with the extraction requires a temperature favorable to the enzymes, and at this temperature certain extracti-ves are driven off `or destroyed partially or wholly. This eifect takes place to a greater extent in the vacuum pan. According vto the present invention the deficiency of '-'the 'high .temperature extract, in respect to these extractives, is compensated for by the addition of the low temperature extract.

Example :L -Fig, .2 illustrates a modification of the process as illustrated in Fig. 1, the purpose of which is Ato still further improve the avor and .aroma of the final extract, whether in the form of .a syrup or a powder. :In Fig. 2 the flow sheet illustrates thelast steps ofthe `process only. The .steps preceding those illustrated may be the same as shown in Fig. 1. A part only of the low temperature extract from the clarifying centrifuge 2U, goes through line 40 to the mixing vessel 3'! which receives the high temperature extract from after oil treatment as indicated at 36, This mixture of extracts is dried on heated rolls as indicated at 38, and pulverized as indicated at 33. This part of the process is the same as in Fig. 1 (and the steps numbered the same) except that only part of the clarified liquor is so treated. The residue of the low temperature extract, clarified at 20, goes through line 4| to a mixing vessel 4Z where it is mixed with coffee oil (preferably partially hydrogenated in order to prevent rancidity) introduced at43, together with a small amount of pulverized coffee extract from the pulverizer 35i-the device of Fig. l-introduced at 44. The ingredients of the mixture may be as follows: Low temperature extract at 30 Baum, 80 parts; dried and pulverized extract, 20 parts; coffee oil, 20 parts. About 20% to 40% of the coffee oil is hydrogenated, the rest being the natural coffee oil. In place of hydrogenated coffee oil, one can use any hydrogenated oil which is tasteless or substantially so. In place of the pulverized coffee extract, it is possible to use gum arabic or other suitable colloid, in propertion of 1/2% to 1% of the dry substance of the mixture in vessel 42. The

mixture in vessel 42 is heated to about 125' but not in any case in excess of 150 F., and the material then treated to give a smooth emulsion.

. 76 -This maybe :accomplished :by passing the mixture through .a homogenizer 4'5 in which the mixture vis forced Athrough a small orifice .ata pressureof :2500 pounds per square inch. Most of the extract pulverized at 39 passes through `line 46 to va blending apparatus 41, which may be any suitable mixing device, into which is introduced throughline :48 the emulsion from the homogenizing apparatus 45. The amount of the emulsion thus blended with the powdered extract may vary quite considerably, say from 0.5% to 5.0% by weight of the dry powder. In order lto obtain a smooth emulsion o-f uniform consistency, it `may be desirable yto repeat the homogenizing operation, in which case, the emulsion from homogenizer may be introduced into mixing vessel 4 9 through line vand there mixed with high temperature .extract introduced through line-5l, and the mixture put through a .second homogenizer 52, and -then introduced into the blending vessel 41 .through line 53. Y

Applicants co-pending application Serial No. 425,551 for Coiee extract, filed January 3, 1942, describes and claims the mixing with the final .coffee extract, Whether in powdered or :syrup form, a certain quantity of natural coffee oil for the purpose of improving the flavor and aroma characteristics of the product. The present invention involves, in respect to Example v3 (Figl 2) an improved method of blending the oil with the extract whereby a smoother .and more uniform blend is obtained.

It will be understood that the processes of EX- amples 1l 2 and 3 may be adapted, by obvious modifications, to the production yof extract in the form of a syrup, instead of in the form of a dry powder, For example, the` step of drying on the heated rolls may be omitted; or a concentrating operation, which does not reduce the `material to .a dry state, may be substituted for it. The introduction of the oil as an emulsion into the extract is, however, particularly desirable Where the extract is ina powdered state.V If oil is introduced into the final extract, :the voil treatment ofthe high temperature extract at `35 may or may not be employed; but if employed, it will bepossible to use any tasteless vegetable oil instead of coffee. In any case, enough of the oil introduced into the material, either at 36 or at 4l, will be hydrogenated to prevent rancidity.

The present invention may be used to advantage in the production of so-called coffee substitutes, that is vegetable extracts from roasted wheat, rye, bran, malt, carmelized sugar, malt extract and molasses or other roasted vegetable matter used for producing extracts from which coffee-like beverages can be made. In such case a closer approximation to the flavor and aroma of coee can be obtained by adding to the material, preferably to the dried and powdered extract a small amount of coffee oil and without a small amount of a hydrogenated vegetable oil ydescribed above in connection with the treatment of coffee extracts.

This application is a continuation-in-part of applicants co-pending application for "Treatment of organic liquids," filed August 23, 1941, as Serial No. 408,052.

I claim:

1. Improvement in the process of making coffee extracts which comprises: subjecting roasted and ground coffee to a soaking operation in cold water; drawing olf the liquid and subjecting the same to repeated freezing and separating operations, giving a low temperature concentrated extract; subjecting the coffee material to a boiling operation; drawing off the extract from the boiling operation; concentrating the same in a Vacuum pan; mixing this high temperature extract with the low temperature extract from the freezing operations; subjecting the coiee material from the cooking operation to a series of extracting operations in counter-current with each other and with said cooking operation in which the more concentrated extract is introduced into the cooking operation; and subjecting the mixture of concentrated high temperature and lowtemperature extracts to a quick drying operation.

2. Process for the production of a beverage extract from roasted vegetable material which comprises: making a cold water extract from said material Vand concentrating the same at relatively loW temperatures; making a hot water extract from the material, concentrating the hot Water extract at higher temperatures than the first mentioned extract, combining both concentrated extracts, and drying the mixture quickly at relatively high temperatures.

3. Improvement in the process of making a concentrated beverage extract from roasted vegetable material which comprises: blending with the concentrated extract a homogenized water emulsion of natural coffee oil.

4. Improvement in the process of making coffee extract which comprises: making an extract from ground roasted coffee blending with the extract a homogenized water emulsion of natural coffee oil.

5. Process of making coffee extract which comprises: extracting a portion of the solubles from 5- the coffee material and concentrating the extract,-

at relatively low temperatures; extracting another portion of the solubles from the coee material and concentrating the extract at relatively high temperatures'making a mixture of said concentrated extracts; quickly drying the combined extracts at relatively high temperatures; and blending with the dry extract some of the concentrated low temperature extract.

6. Process of making coffee extract which com- Cil prises: extracting a portion of the solubles from the coffee material and concentrating the extract, at relatively low temperatures; extracting another portion of the solubles from the coffee material and concentrating the extract at relatively high temperatures making a mixture of said extracts; evaporating the combined extracts to a dry state; and blending with the dry extract an emulsion containing some of said low temperature extract and natural coffee oil.

7. Process of making coffee extract which comprises: extracting a portion of the solubles from the coffee material and concentrating the extract, at relatively low temperatures extracting another portion of the solubles from the coiee material and concentrating the extract at relatively high temperatures, making a mixture of said low temperature and high temperature extracts; evapcrating the combined extracts to a dry state; and blending with the dry extract an emulsion containing some of said low temperature extract natural coffee oil and some of said dry extract.

8. Process of making coffee extract which comprises: extracting a portion of the solubles from the colee material and concentrating the extract, at relatively low temperatures; extracting another portion of the solubles from the coiee material and concentrating the extract at relatively high temperatures making a mixture of said extracts; evaporating the combined extracts to a dry state; homogenizing a mixture of some of said low temperature extract, natural coffee oil and some of the dry extract to form a smooth and uniform emulsion; and blending said emulsion with the rest of the dry extract.

9. In the process of making dry coffee extract which includes making a concentrated liquid extract and thereafter drying the same by application of heat, the improvement comprising introducing into the liquid extract immediately before the drying a small amount of vegetable oil to preserve the volatile flavor giving constituents of the extract and to prevent formation of dust during the said drying step of thc process.

JOHN L. KEILOGG. 

